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![LangChain](https://pica.zhimg.com/50/v2-56e8bbb52aa271012541c1fe1ceb11a2_r.gif)




Elasticsearch
=====




[Elasticsearch](https://www.elastic.co/elasticsearch/)是一个分布式、RESTful搜索和分析引擎。它提供了一个分布式、多租户能力的全文搜索引擎，具有HTTP网络接口和无模式JSON文档。

此教程演示了如何使用与`Elasticsearch`数据库相关的功能。

安装[#](#installation "此标题的永久链接")
-------------------------------

请查看[Elasticsearch安装说明](https://www.elastic.co/guide/en/elasticsearch/reference/current/install-elasticsearch)。

要连接到不需要登录凭据的Elasticsearch实例，请将Elasticsearch URL和索引名称与嵌入对象一起传递给构造函数。

示例：

```python
        from langchain import ElasticVectorSearch
        from langchain.embeddings import OpenAIEmbeddings

        embedding = OpenAIEmbeddings()
        elastic_vector_search = ElasticVectorSearch(
            elasticsearch_url="http://localhost:9200",
            index_name="test_index",
            embedding=embedding
        )

```

要连接到需要登录凭据的Elasticsearch实例，包括Elastic Cloud，请使用Elasticsearch URL格式https：//username：password@es_host：9243。例如，要连接到Elastic Cloud，请使用所需的身份验证详细信息创建Elasticsearch URL，并将其作为名为elasticsearch_url的命名参数传递给ElasticVectorSearch构造函数。

您可以通过登录Elastic Cloud控制台https：//cloud.elastic.co，选择您的部署，并导航到“部署”页面来获取Elastic Cloud URL和登录凭据。

要获取默认“elastic”用户的Elastic Cloud密码：

1. 登录到Elastic Cloud控制台https：//cloud.elastic.co
2. 转到“安全”>“用户”
3. 找到“elastic”用户并单击“编辑”
4. 单击“重置密码”
5. 按提示重置密码

Elastic Cloud URL的格式为https：//username：password@cluster_id.region_id.gcp.cloud.es.io：9243。

示例：

```python
        from langchain import ElasticVectorSearch
        from langchain.embeddings import OpenAIEmbeddings

        embedding = OpenAIEmbeddings()

        elastic_host = "cluster_id.region_id.gcp.cloud.es.io"
        elasticsearch_url = f"https://username:password@{elastic_host}:9243"
        elastic_vector_search = ElasticVectorSearch(
            elasticsearch_url=elasticsearch_url,
            index_name="test_index",
            embedding=embedding
        )

```

```python
!pip install elasticsearch

```

```python
import os
import getpass

os.environ['OPENAI_API_KEY'] = getpass.getpass('OpenAI API Key:')

```

Example[#](#example "Permalink to this headline")
-------------------------------------------------

```python
from langchain.embeddings.openai import OpenAIEmbeddings
from langchain.text_splitter import CharacterTextSplitter
from langchain.vectorstores import ElasticVectorSearch
from langchain.document_loaders import TextLoader

```

```python
from langchain.document_loaders import TextLoader
loader = TextLoader('../../../state_of_the_union.txt')
documents = loader.load()
text_splitter = CharacterTextSplitter(chunk_size=1000, chunk_overlap=0)
docs = text_splitter.split_documents(documents)

embeddings = OpenAIEmbeddings()

```

```python
db = ElasticVectorSearch.from_documents(docs, embeddings, elasticsearch_url="http://localhost:9200")

query = "What did the president say about Ketanji Brown Jackson"
docs = db.similarity_search(query)

```

```python
print(docs[0].page_content)

```

```python
In state after state, new laws have been passed, not only to suppress the vote, but to subvert entire elections. 

We cannot let this happen. 

Tonight. I call on the Senate to: Pass the Freedom to Vote Act. Pass the John Lewis Voting Rights Act. And while you’re at it, pass the Disclose Act so Americans can know who is funding our elections. 

Tonight, I’d like to honor someone who has dedicated his life to serve this country: Justice Stephen Breyer—an Army veteran, Constitutional scholar, and retiring Justice of the United States Supreme Court. Justice Breyer, thank you for your service. 

One of the most serious constitutional responsibilities a President has is nominating someone to serve on the United States Supreme Court. 

And I did that 4 days ago, when I nominated Circuit Court of Appeals Judge Ketanji Brown Jackson. One of our nation’s top legal minds, who will continue Justice Breyer’s legacy of excellence.

```

